Resilient stop for screw elevators



March 4, 1952 c, PANTER 2,587,757

RESILIENT STOP FOR SCREW ELEVATORS Filed Nov. 9, 1950 3 Sheets-Sheet 1Summer Car/ for; fer

1! E attorney March 4, 1952 c, PANTER 2,587,757

RESILIENT STOP FOR SCREW ELEVATORS Filed NOV. 9, 1950 3 Sheets-Sheet 2 31 i H I! l 12 19 ll l 1| I8 4 H 25 .1 1 l /o I 32 Q 23 l l A 27 \&

'lnventor Car/ Fan 7% March 1952 c. PANTER RESILIENT STOP FOR SCREWELEVATORS 3 Sheets-Sheet 3 Filed NOV. 9, 1950 3nventor Cor/ for? 7e/"Patented Mar. 4, 1952 UNITED STATES PATENT OFFICE Carl Panter, .Toledo,Ohio, assignor to Haughton Elevator Company, Toledo, 0hio,.-a.corporation ApplicationNovember 9, 1950, Serial-No.-1-94,-852 '3 claims.(01. 187-24) This invention relates to screw .driven elevators and inparticular to a simple mechanism for safely stalling the drive motor ofa screw driven elevator should the elevator car overrun its normal upperlimit of travel. I

It is customary in screw driven elevators to provide, on the bottom endof the elevating screw, a stop which by jamming against a rotatingdrivenutas the elevator reaches its extreme upper limit of travel stallsthe motor. elevator operates at slow speed with a relatively low speedmotor this jamming at the end of the travel is not particularlydangerous but nevertheless severely overloads parts of the mechanism andaccelerates the wear on thedrivemechanism, Furthermore, if the threadsof the nut driving the screw are worn this sudden jamming at the end ofthe stroke may strip the threads in the nut thus robbing the elevatorcar of its support and allowing it to drop.

, The principal object of this invention is to provide a preloadedresile'nt connection in the drive system for a screw-type elevator whichpreloaded resilient connection absorbs the kinetic energy of thte drivemotor and stalls the motor without seriously overloading any portion ofthe elevator drive system.

Another object 'of "the invention is 'to'provide a resilient connection,preferably preloaded, between an elevator support screw and an elevatorear wherebythesupportscrew may rotate against resilient restraintthrough 'a small angle when a stopon the bottom end of the screw jamsagainst end, equipped with a resilient connection that permits the screwto rotate as the stop jams against the nut and by such rotation absorbthe kinetic energy of the drive motor without overloading the elementsof the drive train.

A preferred form of the invention is illustrated in the accompanyingdrawings.

In the drawings:

Figure I is an elevation, partly in section, of the drive mechanism of ascrew-type elevator embodying the invention.

If the Figure II is an enlarged vertical section of the drive mechanismfor the screw-type elevator.

Figure III is a fragmentary elevation of the connection between theelevator support screw and a portion of the elevator car frame.

Figure IV is a horizontal section as seen looking upwardly against theconnection between the screw and ear frame from the line IV-IV of FigureIII.

These specific figures and the accompanying description are intendedmerely to illustrate the invention and not to impose limitations on itsscope. I V V V Ina screw-type elevator embodying the {invention anelevator car having a floor I is supported on a cross beam ,2 that isguided an elevator shaft (not shown) and in support on ascrew threadedcolumn 3 that e'xtend througha gear box A and into av casing 5' xtendingdownwardly through and. beneath a foundation 6. A drive motor I, mounted"on a frame 8, has its armature shaft 9 connected to an input shaft ll]{of the gear box 1. .A brake drum ll mounted on the shaft 9 cooperateswith brake shoes 'l 2 that are actuated by a solenoid I3. The brakeshoes l2 are spring set and are applied to the brake drum I'l wheneverthe power is taken off the motor "I. A .protective (or dust shield) 14extends-over themotor 1 and thegbra'ke. mechanism. V

Referring'now to Figure II the screw threaded elevator support column 3extends through an "internauy threaded drive hill? 15. The flu l; I5 issupport'edon a tapered ronmg'hearing comprising an outer race I5 mountedin a cylindrical insert ll of the gear housing I and an inner-race l 8mounted on a cylindrical portion of the nut l5 and held in place by keys19 whicharesecured by a cap 2|]. Tapered roller bearings 2| interposedbetween the inner and outer races support the elevator car and its loadwhile permitting the nut to turn in raising or lowering the elevatorcar.

The lower portion of the nut I5 is journaled in a cylindrical bore 22 ofa boss 23 raised from the floor of the gear box 4.

A worm wheel 24 formed integrally with the nut I5 engages a worm 25mounted on the input shaft ID of the gear box 4. Rotation Of the motorthus drives through the worm 25 and worm wheel 24 to rotate the nut l5and thus raise or lower the elevator car.

A flanged steel collar 26 loosely sleeved over the end of the screwthreaded column 3 is carried adjacent the lower surface of thecylindrical nut IS with its flanged portion resting on shoulders 21formed by a reduced diameter portion of the bore 22. The steel collar 26is jammed against the lower surface of the rotatable drive nut as aheavy cylindrical pin 28 mounted in and projecting laterally from thelower end of the threaded column 3 engages the flanged collar 26 at theupper limit of travel of the elevator car. The steel collar 26 isinterposed between the heavy cylindrical pin 28 and the lower surface ofthe nut IE to prevent the pin from gouging the nut as the motor isstalled by jamming of the drive mechanism at the upper limit of travel.

Referring now to Figures 11, III and IV the upper end of the threadedelevator support column 3 is engaged in a resilient connection attachedto the cross member 2 of the elevator car frame. This connectioncomprises a plate 29 that is attached to the cross member 2 and that hasfixed downwardly directed lugs 30. A cross arm 3| mounted on a pin 32extending through the upper end of the threaded support column 3 has itsarms 33 in abutting relation to the sides of the downwardly directedlugs 30 such that the arms are urged against the abutments duringdownward travel of the elevator.

The arms 33 are resiliently held against the lugs 3|] by a pair ofhelical compression springs 34 and the lugs 30. Tightening of nuts 36compresses the springs 34, held between the heads 31 of the bolts 35 andthe arms 33 of the cross member 3| to force the arms 33 against the lugs30 so as to preload the springs and resiliently hold the arms 33 againstthe lugs 3|].

A second plate 38 having a central hole to accommodate the threadedsupport column 3 is located immediately below the cross member 3| andthe lugs 30 and is attached to and spaced from the first plate 29 by aplurality of threaded studs 39 and spacers 40. The plate 38 prevents thesupport column 3 from being disengaged from the first plate 29 shouldthe elevator car stick in the hatchway or strike buffers at the bottomof the hatchway before the support column 3 itself is stopped.

In this arrangement, during upward travel of the elevator, the supportcolumn 3 is held from turning relative to the elevator car by thepreload force of the compression springs 34. Should the elevator overrunits upper landing position the heavy cylindrical pin 28 at the lower endof i the column drives the steel collar 26 against the nut I5 thusjamming the screw 3 in the nut l5. During deceleration of the motor Ithe nut l5 continues to turn thus turning the screw 3 against the forceof the springs 34. The force required from the drive motor to overcomethe resistance of the springs 34 is much greater than the availablemotor torque so that the motor is quickly stalled. The kinetic energystored in the motor armature is absorbed partly by the springs 34,partly by friction between the upper surface of the cross member 3| andthe lower surface of the first plate 29, and partly by friction betweenthe worm 25 and the worm wheel 24. The friction forces, however, aresmall enough so that upon reversal of the motor 1 the column 3 rotatesback to its normal position and the jam between the nut I5 and thethreads on the column 3 is released.

This arrangement of a resilient connection in an elevator drive systemprevents extremely high jamming forces that would occur if the motorwere suddenly stopped when the screw jams at the upper end of itstravel. This elimination of the extremely high shock forces reduces theamount of wear to be expected and the danger of shearing the threads inthe nut l5.

Various modifications in the detail of the resilient member of the drivesystem may be made without departing from the spirit and scope of theinvention.

Having described the invention, I claim:

I 1. In an elevator, in combination, an elevator car frame, a screwthreaded column supporting the car frame, a base, a nut threaded on thecolumn and journaled in the base, means for driving the nut, a memberfixed to the bottom of the column and engageable with the nut at the endof the upward travel of the elevator frame, a cross member on the top ofthe column, stops on the frame engaging the cross member, and resilientmeans for holding the cross member against the stops during upwardtravel of the elevator and absorbing the shock of the nut driving meanswhen said member engages the nut.

2. In an elevator, in combination, an elevator car frame, a' screwthreaded column supporting the car frame, a base, a nut threaded on thecolumn and journaled in the base, means for driving the nut, a memberfixed to the bottom of the column and adapted to engage the nut, a crossmember fixed to the upper end of the column, a pair of stops fixed tothe car frame and engaging the cross member, a pair of springs urgingsaid cross piece against the fixed stops, and means for supporting thesprings.

3. In an elevator, in combination, an elevator car frame, a screwthreaded column for supporting the frame, a base, a nut threaded on thecolumn and journaled in the base for supporting the column, a motoroperatively connected to the nut, means on the bottom of the column tolock with the nut when the column reaches its upper limit of travel, across arm on the upper end of the column, a pair or stops on the frame,bolts extending through said stops and the adjacent ends of the crossarm, and springs sleeved onsaid bolts for urging the cross arm againstthe stops and permitting said column to rotate against the force of thesprings when said means locks the columnto the nut.

CARL PANTER.

No references cited.

